Ignition timing control for internal-combustion engines



IGNITION TIMING CONTROL FOR INTERNAL-COMBUSTION ENGINES Filed June 4, 1948 INVENTOR. .v Mar/0n Mafia/y" BY @om9W ATTORNEYS Patented Nov. 28, 1950 IGNITION TIMING CONTROL FOR INTER- NAL-COMBUSTION ENGINES Marion Mallory, Detroit, Mich, assignor to The Mallory Research Company, Detroit, Link, a corporation of Michigan Application June 4, 1948, Serial No. 31,164

l 2 Claims.

This invention relates to means for controlling the ignition timing in an internal combustion engine and more particularly to controlling such timing when the engine is being decelerated or is acting as a brake.

In my prior patent for Ignition Timing Control Means for Internal Combustion Engines, issued December 30, 1941, Patent No. 2,268,490, there is disclosed timing control means comprising a suction operated device connected to the carburetor in such a way as to obtain the desired advancement or retardation of the spark under certain conditions. However, in this device it was found that when the engine was operating at high speeds with the throttle closed, as, for example, when decelerating or going down hill, thespark was not suiiiciently advanced with the result that there would be danger of explosions in the mufier under such circumstances.

The present invention is an improvement over that disclosed in my prior patent, by which improvement the proper advancement of the spark is secured when the engine is running at high speeds with the throttle closed.

In the accompanying drawings forming a part of this specification, there is shown a sectional view of a carburetor with timing means connected thereto and shown somewhat diagrammatically and embodying the improvement which constitutes this invention.

The carburetor, as shown in the drawings, is provided with an air inlet I and an air outlet 2, which is fitted against the intake manifold of an internal combustion engine. The carburetor is provided with a small Venturi tube 3 which has a fuel inlet 4 thereinto. There is also provided a larger Venturi tube 5. Between these tubes and the engine manifold there is the usual throttle valve 8. A pipe 1 provides a passageway from the carburetor to a suction device 8 provided with a diaphragm 9 normally protruded against the force of atmospheric air by a spring Ill. The diaphragm is connected by a rod H to a disk I! carrying a make-and-break arm I 3, which is operated by a cam I. As shown in the drawings, the cam is constantly turning in an anti-clockwise direction. It will be seen that when the air pressure behind diaphragm 9 is sufficiently reduced so that atmospheric pressure moves the diaphragm against the pressure of spring [0. disk I! carries a make-and-break device in a clockwise direction, thus advancing the timing oi. the ignition.

Tube 1 is connected by suitable passageways in the carburetor to an opening into the Venturi tube 3 and preferably a restriction It with the passageway to an opening l1, which enters the carburetor immediately on the intake side of the throttle valve when the throttle valve is closed. As shown in the drawings, it will be readily seen that when the throttle valve opens opening I 'I will be on the engine or manifold side of the throttle valve.

There is also provided an opening 18- into the passageways from the manifold side of the throttle valve when the throttle is closed. This opening I8 is smaller than opening I]. The openings are so proportioned in connection with the size of the diaphragm and the strength of the spring in that when the engine is idling the air entering opening II will effectually counteract the suction from opening 18, so that the spark will be fully retarded. However, when the engine is operating much more rapidly than its ordinary idling speed, the suction in the manifold and at opening it is so increased that in spite of the opening at it the force of spring in is sufliciently overcome to partly advance the spark and thus prevent the objectionable explosions in the muiiier.

The drawings shown the opening it slightly larger than restriction I6, but whether controlled by restriction id or other means, the relative effective sizes of the connections from the Venturi tube and opening H to the vacuum device will vary in different carburetors, as described in my former patent, the improvement over that patent consisting in the addition of opening l8 into the passageway, whereby the defective operation during the high speed movement of the engine with the throttle closed, is overcome. It will be readily understood that various modifications may be made as described in my former patent and that the most essential features are the relations of openings IT and It to the throttle valve, whereby the opening ll results in the full retardation of the spark during normal idling and opening 18 overcomes this operation and advances the spark when the engine is speeded up above normal idling speed with the throttle closed, the amount of the advance depending upon the amount of the speeding up of the engine.

A choke valve 22 may be operated by a rod 23 attached to an arm 24 on the valve pivot. When the choke is closed by moving rod 23 to the left, a pin 25 on another arm 26 from the valve pivot first moves upward in slot 21 in the stem of plunger 28. Before the valve is closed, the pin 25 reaches the top of slot 2'! and thereafter raises the plunger 28 to vent pipe I through opening 29, thus nullifying the tendency of openings I 8, I, i! and I! to create a vacuum in pipe I and advance the spark while the choke is closed.

What I claim is:

1. In an internal combustion engine having an intake manifold, an ignition timer, a carburetor comprising an air intake, and air outlet to the engine manifold, a fuel inlet between said air inlet and outlet, and a throttle valve between the fuel inlet and the manifold, a suction controlled means for advancing and retarding the timer, and means providing a constantly open passageway from said suction means to an opening into the carburetor at a point on the engine side of the throttle valve when the valve is open and on the other side of the throttle 15 Number 4 valve when the valve is closed, and to a smaller opening on the engine side of the throttle valve in all positions of the valve.

2. An engine in accordance with claim 1 and in which the carburetor comprises a Venturi tube and an opening from said tube into said passageway.

MARION MALLORY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date 2,365,768 Mallory Dec. 20, 1944 

